By Clayton Botkin
Avian influenza is a disease known to circulate in populations of wild waterfowl, commonly the dabbling ducks. For those unfamiliar with this group of birds, it includes the mallards, pintails and teal. Avian Influenza can cross from wild birds into captive birds readily, through contact with birds or their droppings. In Washington State, it was transferred from a killed green wing teal to a Gyr falcon through consumption, and leading to death. Highly pathogenic avian influenza can lead to mortality in a flock up to 100%.
Typically, these serious infections are caused by viruses of the H5 or H7 type. We have recently witnessed outbreaks of these viruses around the globe. They appear routinely in Asia, spread through China, Thailand, Korea and Vietnam. We have also seen outbreaks in France, Great Britain, Germany and the Netherlands. North America has been far from immune to outbreaks as well. Mexico has had an ongoing battle with the virus since the mid-1990’s, and has attempted to use vaccination as a solution, while the United States faced a massive outbreak requiring the cull of almost 50 million birds. Canada also faced their fourth outbreak of the virus in the last 10 years, but contained it quickly with losses of only about 250,000 birds in 11 commercial poultry farms in one of the most densely populated poultry producing areas in North America.
The response to an Avian Influenza detection is largely dependent on the policies of the governing country. In most developed nations, it involves a combination of destruction of the affected flock, movement controls and establishment of control zones surrounding the affected premises, some form of active surveillance in known surrounding populations, and possibly stamping out. With recent outbreaks, and advancements in technologies, stamping out seems to be rarely practiced. This is likely due to new rapid and highly sensitive testing. This shift in response is a large benefit to small flock owners as it is unlikely we will see any massive culls of unaffected birds. Active surveillance typically involves swabbing of a designated portion of birds on a suspect or nearby premises to an infected flock. Swabs are usually of a synthetic nature, and sampled from the trachea and cloaca of individual birds, and transported in a special media to a lab. At the lab, swabs undergo a thorough process of amplification and screening, and then various testing procedures. Most animal diagnostic labs that have the designation to perform these tests can have results within a day. It is important to note, however, these swabs will likely only test positive if the bird is actively shedding virus at the time the sample was taken.
The virus infects its host, incubates and manifests itself rather quickly. The H5N2 that blasted its way across North America in 2014-15 had an incubation period of between two and seven days, depending on the affected species. Initial reports of suspected illness from infected farms was typically through major spikes in mortality. This is likely the key indicator for small flock owners to be wary of. If you see an increase in mortality in your flock, it is extremely important to contact your local animal health agency.
Most government agencies are prepared to support bird owners who self-identify with issues related to Avian Influenza. It is always a good idea to have pre-established relationships with these officials prior to an event occurring. Contact local and regional managers and ask if they have a plan to respond to a suspected case and what that plan entails. It is typically publicly available information. They are also an excellent resource on the other disease pressures in your area, and what measures you can take to reduce the risk to your birds becoming infected. This is definitely a disease worthy of prevention.